encapsulate fft chain in its own class

csdr/chain/fft.py

@@ -0,0 +1,15 @@
+from csdr.chain import Chain
+from pycsdr import SocketClient, Fft, LogAveragePower, FftExchangeSides, CompressFftAdpcm
+
+
+class FftChain(Chain):
+    def __init__(self, port, fft_size, fft_block_size, fft_averages, fft_compression):
+        workers = [
+            SocketClient(port=port),
+            Fft(size=fft_size, every_n_samples=int(fft_block_size)),
+            LogAveragePower(add_db=-70, fft_size=fft_size, avg_number=fft_averages),
+            FftExchangeSides(fft_size=fft_size),
+        ]
+        if fft_compression == "adpcm":
+            workers += [CompressFftAdpcm(fft_size=fft_size)]
+        super().__init__(*workers)